This invention relates to electrical isolators.
In the particular context of feeder pillars used in electrical distribution networks the isolators used in said pillars present a significant quantity of exposed bare metal, which is a potential hazard. Such isolators comprise a bridging contact capable of being tightened into engagement with the input and output conductors through the use of suitable tightening devices designed to apply pressure to the bridging contact to hold it in firm electrical engagement with the input and output conductors. In view of the exposed bare metal it is current practice for the tightening devices to be tightened and loosened by means of a long insulated pole, the contact being hinged out of its bridging position when the devices are loosened.
Equivalent isolators used on the continent of Europe are provided with better insulation than those in the United Kingdom and are thus safer from an operator's point of view. However, the continental isolators rely on springs to apply the required contact pressure between the bridging contact and the input and output conductors. Springs relax with aging, and there is thus the potential danger of the contact pressure being reduced to a limit below that required for proper safety of operation.
The object of the present invention is to provide an isolator that does not suffer this disadvantage, and that is capable of being insulated to a high standard of safety and also of being provided with additional safety interlocks.